JP6268557B2 - Casting method and casting apparatus - Google Patents

Description

  The present invention relates to a casting method and a casting apparatus used for forming a product based on a low pressure casting method.

  As this type of casting method and casting apparatus, for example, there is one described in Patent Document 1. The casting method (and casting apparatus) described in Patent Document 1 includes a sealed chamber that covers a mold, and uses a vacuum pump and a vacuum tank to suck and reduce the pressure inside the sealed chamber and the stalk. By pressurizing the inside and filling the cavity with the molten metal, the casting speed of the molten metal is increased and the hot water performance is improved.

Japanese Patent No. 2933255

  However, in the conventional casting method (and casting apparatus) as described above, since it is necessary to depressurize the inside of the sealed chamber including the cavity of the mold and the inside of the stalk at the same time, the depressurizing apparatus having a large exhaust capacity. However, there is a problem that it is difficult to shorten the casting cycle time because the equipment cost and the manufacturing cost increase and it takes time to lower the vacuum tank to a certain decompression level. It was a problem to solve various problems.

The present invention has been made paying attention to the above-mentioned conventional problems, and it is possible to reduce the equipment cost and the manufacturing cost by performing the minimum necessary suction, and the casting cycle time can be reduced . It aims at providing the casting method and casting apparatus which can implement | achieve shortening.

The casting method according to the present invention uses a casting apparatus having a structure in which a mold having a cavity is disposed on the upper side of a holding furnace containing molten metal, and when forming a product based on the low pressure casting method, the inside of the holding furnace is gasified. Pressurize and raise the molten metal to the vicinity of the sprue of the cavity, and then suction and depressurize the cavity, pressurize the holding furnace further to fill the cavity with the molten metal, and when the filling of the molten metal is completed The above-described configuration is used as a means for solving the conventional problems.

  A casting apparatus according to the present invention includes a plurality of casting machines each including a holding furnace containing molten metal, a mold having a cavity, and a pressurizing unit that pressurizes the inside of the holding furnace with gas. A decompression means for sucking and decompressing the inside of the cavity is provided. In the casting apparatus, the decompression means branches from a vacuum tank having an intake pipe on the inlet side and an exhaust pipe on the outlet side, a vacuum pump connected to the exhaust pipe of the vacuum tank, and an intake pipe of the vacuum tank. And a branch pipe communicating with the cavity of each casting machine, and an on-off valve for opening and closing the middle of each branch pipe.

  According to the casting method and the casting apparatus according to the present invention, since the necessary minimum suction is performed, the decompression means can be simplified, the equipment cost and the manufacturing cost can be reduced, and the casting cycle time can be shortened. Can be realized.

It is a section explanatory view of a casting device showing a 1st embodiment of the present invention. It is a top view explaining the front suspension member for vehicles as an example of a product, and a sectional view (B) of a hollow part based on an AA line. It is a block diagram which shows the process of the casting method of this invention. It is a timing chart explaining the operation | movement of the vacuum pump shown in FIG. 1, the pressure of a vacuum tank, the pressurization pressure of a holding furnace, and the pressure of a chamber. It is sectional explanatory drawing of the casting apparatus which shows 2nd Embodiment of this invention. It is sectional explanatory drawing of the casting apparatus which shows 3rd Embodiment of this invention. It is a timing chart explaining the change of the pressure of the vacuum tank shown in FIG. 6, the applied pressure of a holding furnace, and the pressure of a chamber. It is sectional explanatory drawing of the casting apparatus which shows 4th Embodiment of this invention. It is a timing chart explaining the operation | movement of the vacuum pump shown in FIG. 8, the pressure of a vacuum tank, the pressurization pressure of the holding furnace in each casting machine, and the change of the pressure of a chamber. It is sectional explanatory drawing (A) of the casting apparatus which shows 5th Embodiment of this invention, and the expanded sectional view (B) of a metal mold | die. It is sectional explanatory drawing (A) of the casting apparatus which shows 6th Embodiment of this invention, and an expanded sectional view (B) of a metal mold | die.

<First Embodiment>
A casting apparatus 1 shown in FIG. 1 includes a base 2, a plurality of guide posts 3 erected on the base 2, a stationary platen 4 fixed between the guideposts 3, and between the stationary platen 4 and the base 2. A holding furnace 5 is provided. The casting apparatus 1 includes a movable plate 6 that is driven up and down along the guide post 3, and a frame 7 that is installed on the upper end of the guide post 3, and the movable plate 6 is interposed between the frame 7 and the movable plate 6. Is provided with a hydraulic cylinder 8 for moving up and down.

  Further, the casting apparatus includes a mold 9 and a chamber 10 that hermetically accommodates the mold 9 between the movable platen 6 and the fixed platen 4. The mold 9 includes an upper mold 9U fixed to the movable platen 6 and a lower mold 9L fixed to the fixed platen 4, and a cavity 9C that is a casting space is formed therebetween. Further, the lower mold 9L is provided with a gate 11 opened at the bottom of the cavity 9C.

  On the other hand, the chamber 10 includes an upper frame 10U that surrounds the upper mold 9U in the movable platen 6 and a lower frame 10L that surrounds the lower mold 9L in the fixed platen 4. A sealed space is formed between them.

  The holding furnace 5 contains the molten metal M, and is provided with a lid 5A combined with the lower side of the fixed platen 4, a heating means (not shown), and the like, and the molten metal M is supplied to the cavity 9C. A stalk 12 is provided for this purpose. The stalk 12 is in a state where the upper end portion communicates with the gate 11 of the mold 9 and the lower end portion is immersed in the molten metal M.

  Further, the casting apparatus 1 controls the pressurizing means 13 for pressurizing the inside of the holding furnace 5 with gas, the decompression means 14 for sucking and decompressing the inside of the cavity 9C of the mold 9, and these. Control means 15 is provided.

  Although the detailed illustration is omitted, the pressurizing means 13 is constituted by a tank storing a pressurizing gas such as an inert gas, an on-off valve, and piping, and the pressurizing gas is supplied into the holding furnace 5 by a supply pipe 13A. The pressure is supplied to the surface of the molten metal M. As a result, the molten metal M is filled into the cavity 9 </ b> C through the stalk 12.

Decompression means 14, a vacuum tank 14C having an exhaust pipe 14B into and exit side has an intake pipe 14A on the inlet side, and a vacuum pump 14D connected to an exhaust pipe 14B of the vacuum tank 14C, the intake pipe 14A An on-off valve 14E that opens and closes is provided. The decompression means 14 of this embodiment sucks the inside of the cavity 9 </ b> C of the mold 9 and decompresses the suction pipe 14 </ b> A through the upper frame 10 </ b> U of the chamber 10 and sucks the inside of the chamber 10. Further, the vacuum tank 14C of the decompression means 14 has a capacity sufficiently larger than the total volume of the space in the chamber 10 (the space excluding the mold 9) and the cavity 9C.

The control unit 15 controls the operation of the vacuum pump 14D and the on-off valve 14E of the pressurizing unit 13 and the depressurizing unit 14, in addition to the hydraulic cylinder 8 that drives the movable plate 6 up and down, and an ejector mechanism for product release ( The operation of the drive source (not shown) is also controlled.

  In the casting method and casting apparatus of the present invention, as an example, a front suspension member (hereinafter referred to as “suspension member”) SM for automobiles as shown in FIG. 2 can be cast. The suspension member SM is a skeletal member for connecting an automobile body and axle and simultaneously loading an engine. The illustrated example includes a front cross member portion M1, a rear cross member portion M2 on the body side, The left and right side member portions M3 and M3 are integrally provided. The suspension member SM is made of, for example, an aluminum alloy.

  In addition, the suspension member SM has a hollow shape (closed cross-section structure) as shown in FIG. 2 (B) in the cross member portions M1, M2 and the side member portion M3 between the cross member portions M1, M2. It has become. For forming this hollow portion, a core disposed in the cavity 9C is used. Such a suspension member SM realizes strength improvement and weight reduction, and is thin and relatively large as a casting.

Next, the casting method according to the present invention will be described together with the operation of the casting apparatus 1 described above.
The casting method of the present invention forms a product based on the low pressure casting method using a casting apparatus 1 having a structure in which a mold 9 having a cavity 9C is disposed above a holding furnace 5 containing a molten metal M. is there. In this casting method, the inside of the holding furnace 5 is pressurized with gas so that the molten metal M is raised to the vicinity of the gate 11 of the cavity 9C. Thereafter, the inside of the cavity 9C is sucked and depressurized, and the inside of the holding furnace 5 is further pressurized to fill the cavity 9C with the molten metal M. Then, the decompression in the cavity 9C is stopped after the preset filling time has elapsed, and the pressurization in the holding furnace 5 is stopped as the solidification of the molten metal M is completed.

Specifically, in the casting method, as shown in FIG. 3, the mold is closed in the first step S1. In this step S1 , the movable platen 6 is lowered to close the upper mold 9U and the lower mold 9L, and the upper frame 10U and the lower frame 10L are closed to seal the chamber 10. At this time, as shown in FIG. 4, the decompression means 14 operates the vacuum pump 14D for a predetermined time, sucks the inside of the vacuum tank 14C, and maintains the vacuum tank 14C at a constant decompression level.

Next, the casting method starts pressing 1 in step S2. In this step S2 , the inside of the holding furnace 5 is pressurized with gas by the pressurizing means 13, and the molten metal M is raised to the vicinity of the gate 11 of the cavity 9C. That is, the pressurization 1 shown in FIG. 4 is based on the pressure which raises the molten metal M to the vicinity of the gate 11 of the cavity 9C.

Moreover, a casting method starts pressure reduction while starting the pressurization 2 in process S3. In this step S3, the inside of the holding furnace 5 is further pressurized by the pressurizing means 13 , and the inside of the cavity 9C is sucked and decompressed by the decompression means 14. That is, the pressurization 2 shown in FIG. 4 is due to the pressure at which the molten metal M is filled in the cavity 9C. At this time, since the decompression means 14 is in a decompressed state in advance in the vacuum tank 14C, by opening the on-off valve 14E, the interior of the chamber 10 is aspirated rapidly, and the interior of the cavity 9C is also abruptly aspirated accordingly. And depressurize.

  Further, in the casting method, after elapse of a preset filling time, the decompression is stopped in step S4, and the pressurization is stopped in step S5 along with the completion of solidification of the molten metal M. The filling time and solidification time of the molten metal M can be obtained in advance by experiments or the like, and may be set in the timer of the control means 15 as control data for the decompression means 14 and the pressurization means 13. As a specific example, when the product is the suspension member SM shown in FIG. 2, the filling time of the molten metal M is about 2 to 4 seconds, and the solidification time of the molten metal M is about 25 to 35 seconds. These times are appropriately set according to the shape and size of the product.

In this step S4 , the on-off valve 14E of the decompression means 14 is closed to stop the decompression in the cavity 9C. Moreover, in process S5, the pressurization means 13 is stopped and the pressurization in the holding furnace 5 is stopped.

  Thereafter, in the casting method, after opening the mold in step S6, the product is taken out in step S7. That is, in step S6, the upper die 9U is raised together with the movable platen 6 to open the die 9, and in step S7, the product is released by an unillustrated ejector mechanism, and the product is taken out by an appropriate unloading mechanism.

In the casting method and casting apparatus 1 described above, the inside of the holding furnace 5 is pressurized to raise the molten metal M to the vicinity of the gate of the cavity 9C, and then the molten metal M is removed by decompression in the cavity 9C and additional pressurization in the holding furnace 5. Since the filling is performed, the decompression unit 14 performs suction of the total volume of the space in the chamber 10 (the space excluding the mold 9) and the cavity 9C, that is, the necessary minimum suction. Thereby, said casting method and casting apparatus 1 can aim at reduction of an installation cost and a manufacturing cost by simplifying the decompression means 14 .

  More specifically, in the casting method and casting apparatus 1 described above, since the suction amount of the decompression means 14 can be reduced, the vacuum tank 14C has a sufficient remaining capacity. That is, as shown in FIG. 4, the vacuum tank 14C does not return to atmospheric pressure when the pressure in the cavity 9C is reduced during the first casting, and maintains a predetermined pressure reduction level. Therefore, when the next casting is performed, the vacuum tank 14C can be returned to the initial pressure reduction level in a short pressure reduction time (operation time of the vacuum pump 14D). Thereby, in said casting method and casting apparatus 1, shortening of the cycle time of casting is realizable.

  In the casting method and the casting apparatus 1 described above, the molten metal M is filled up by the rapid pressure reduction in the cavity 9C and the additional pressurization in the holding furnace 5 after raising the molten metal M to the vicinity of the gate 11; The hot metal flowability in the cavity 9C is very good, and a product such as a thin and relatively large suspension member SM as shown in FIG. 2 can be molded well.

  In particular, in the casting apparatus 1 described above, the cavity 9C of the mold 9 is a casting space for molding a suspension member SM for automobiles. Can be obtained.

  Furthermore, in the casting method and casting apparatus 1 described above, since the decompression in the cavity 9C is stopped after a preset filling time has elapsed, when the suspension member SM having a hollow portion as shown in FIG. The decompression means 14 can be stopped before gas is generated from the forming core. Thereby, contamination of the decompression means 14 by the core gas (tar) can be prevented in advance.

  5-9 is a figure explaining other embodiment of the casting method and casting apparatus concerning this invention. In the following embodiments, the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

Second Embodiment
The casting apparatus 1 shown in FIG. 5 does not have the chamber (10) described in the first embodiment, and forms an exhaust passage 9D that allows the cavity 9C to communicate with the outside in the upper mold 9U that constitutes the mold 9, thereby reducing the pressure. The intake pipe 14A of the means 14 is connected to the exhaust passage 9D.

  The casting apparatus 1 can obtain the same operation and effect as the first embodiment, and the suction amount by the decompression means 14 is further reduced, so that the decompression time of the vacuum tank 14C is further shortened, and the casting process is reduced. Realize further shortening of cycle time.

<Third Embodiment>
The casting apparatus 1 shown in FIG. 6 has the same basic configuration as that of the first embodiment, and a molten metal sensor that detects completion of filling the molten metal M into the cavity 9C in the upper mold 9U constituting the mold 9. 16 is provided. The molten metal sensor 16 is a temperature sensor, for example, and is provided at a position farthest from the gate 11, and the measured value is input to the control means 15. The control means 15 determines that the filling of the molten metal M into the cavity 9C is completed when the measured temperature of the molten metal sensor 16 exceeds a predetermined value. Moreover, the molten metal sensor 16 may use a sensor that is energized when the molten metal M comes into contact therewith.

  In the casting method using the casting apparatus 1 described above, as in the first embodiment, the inside of the holding furnace 5 is pressurized with gas to raise the molten metal M to the vicinity of the gate 11 of the cavity 9C, and then the cavity 9C. While the inside is sucked and depressurized, the inside of the holding furnace 5 is further pressurized to fill the cavity 9 with the molten metal M. In the casting method, the decompression of the cavity 9C is stopped when the molten metal sensor 16 detects completion of the filling of the molten metal M within a preset filling time.

  According to the casting method and the casting apparatus 1 described above, the same operation and effect as in the previous embodiment can be obtained, and the decompression means 14 can be stopped earlier than a preset filling time. Thereby, as shown in FIG. 7, the casting method and the casting apparatus 1 described above maintain the reduced pressure level of the vacuum tank 14 </ b> C lower than that of the first embodiment (in the case of no sensor), and the chamber 10. The decompression level is maintained high.

  This means that excessive suction is eliminated as much as possible. That is, if the pressure reduction level of the vacuum tank 14C is kept low, the next pressure reduction time (vacuum pump operation time) is shortened. The reason why the reduced pressure level of the chamber 10 is kept high is that the inside of the chamber 10 is sufficiently depressurized and no extra depressurization is performed. As a result, the casting method and the casting apparatus 1 described above can reduce the decompression time and the casting cycle time.

<Fourth embodiment>
A casting apparatus 101 shown in FIG. 8 includes a plurality of casting machines 1 each including a holding furnace 5 in which a molten metal M is stored, a mold 9 having a cavity 9C, and a pressurizing unit 13 that pressurizes the inside of the holding furnace 5 with gas. A stand (three in the illustrated example) is provided. The casting machine 1 has the same basic configuration as the casting apparatus 1 described in the first to third embodiments. Further, the casting apparatus 101 includes a decompression unit 114 for sucking and decompressing the inside of the cavity 9C of each casting machine 1, and a control unit 15 for controlling the pressurization unit 13 and the decompression unit 114.

  The decompression means 114 includes a vacuum tank 14C having an intake pipe 14A on the inlet side and an exhaust pipe 14B on the outlet side, and a vacuum pump 14D connected to the exhaust pipe 14B of the vacuum tank 14C. The decompression means 114 includes a branch pipe 114A that branches from the intake pipe 14A of the vacuum tank 14C and communicates with the cavity 9C of each casting machine 1, and an on-off valve 14E that opens and closes the middle of each branch pipe 114A. . In the illustrated example, the branch pipe 114 </ b> A is connected to the chamber 10 and communicates with the cavity 9 </ b> C through the chamber 10.

  The control means 15 controls the operation of the pressurizing means 13 of each casting machine 1, the vacuum pump 14D of the decompressing means 114, and the on-off valves 14E.

  The casting apparatus 101 forms a product with each casting machine 1 based on the casting method described in the first and third embodiments. At this time, as shown in FIG. After the vacuum tank 14C is sucked to the initial reduced pressure level, casting is performed by the first machine of the casting apparatus 1.

That is, in the casting machine 1 (No. 1 machine) shown on the left side in FIG. 8, the inside of the holding furnace 5 is pressurized with gas by the pressurizing means 13 to raise the molten metal M to the vicinity of the gate 11 of the cavity 9C. Next, the on-off valve 14E of the decompression means 114 is opened and the inside of the cavity 9C is suddenly sucked and decompressed, and the inside of the holding furnace 5 is further pressurized by the pressurizing means 13 to fill the molten metal 11 into the cavity 9C. . Thereafter, after the preset filling time has elapsed, the on-off valve 14E of the decompression means 14 is closed to stop the decompression in the cavity 9C, and the pressurization in the holding furnace 5 by the pressurization means 13 is stopped as the solidification of the molten metal M is completed. .

  In addition, the casting apparatus 101 operates the vacuum pump 14D to return the inside of the vacuum tank 14C to the initial reduced pressure level. At this time, the casting apparatus 101 can return to the initial pressure reduction level in a short pressure reduction time (operation time of the vacuum pump 14D), as in the previous embodiment.

  Next, the casting apparatus 101 performs the same casting in the casting machine 1 (No. 2 machine) shown in the center in FIG. 8, and then performs the same casting in the casting machine 1 (No. 3 machine) shown on the right side in FIG. Thereafter, casting is repeated in the same order.

  As described above, the casting apparatus 101 and the casting method can realize shortening of the decompression time and casting cycle time in one casting machine 1, so that continuous casting using a plurality of casting machines 1 is efficient. Can be done well. Moreover, since this casting apparatus 101 uses the common decompression means 114, it is possible to greatly reduce the installation area, to realize reduction in equipment costs and manufacturing costs, simplification of maintenance management, and the like. Can do.

<Fifth Embodiment>
The casting apparatus 1 shown in FIG. 10A has the same basic configuration as that of the first embodiment, and the cavity 9C of the mold 9 is a casting space for molding the cylinder head of the internal combustion engine.

  The mold 9 of this embodiment includes a horizontal mold (slide core) 9S divided into a plurality of parts between an upper mold 9U and a lower mold 9L, and a cavity 9C corresponding to the cylinder head is formed between them. Yes. Each horizontal mold 9 </ b> S can be advanced and retracted with respect to the mold center by a respective driving device 20 disposed outside the chamber 10.

  Each drive device 20 includes a cylinder 21 and a drive rod (cylinder rod) 22 that is reciprocated in the horizontal direction by the cylinder 21. The drive rod 22 slidably penetrates the lower frame 10L of the chamber 10 and is connected to the horizontal mold 9S. A seal structure for maintaining the airtightness in the chamber 10 is provided in a through portion of the drive rod 22 in the chamber 10. The chamber 10 in this embodiment has a space for retracting the horizontal mold 9 </ b> S between the mold 9.

  In the cavity 9C, as shown in FIG. 10 (B), a core N1 for forming an upper concave portion of the cylinder head, a core N2 for forming a water jacket, and a plurality of ports for forming a port. A core N3 is arranged. The port forming core N3 is integrally provided with a baseboard portion NH positioned between the horizontal die 9S and the lower die 9L.

  The casting apparatus 1 having the above-described configuration pressurizes the inside of the holding furnace 5 to raise the molten metal M to the vicinity of the pouring gate of the cavity 9C based on the above-described casting method, and then reduces the pressure in the cavity 9C and the inside of the holding furnace 5. The molten metal M is filled by additional pressurization.

Thereby, the casting apparatus 1 implement | achieves reduction of the installation cost and manufacturing cost by simplification of the decompression means 14 , and shortening of the cycle time of casting similarly to previous embodiment. Moreover, since the casting apparatus 1 stops the decompression in the cavity 9C after the preset filling time has elapsed, the decompression means 14 is stopped before the gas is generated from the cores N1 to N3, and the cores N1 to N3. Contamination of the decompression means 14 with gas can be prevented in advance.

  Furthermore, since the casting apparatus 1 raises the molten metal M to the vicinity of the pouring gate 11 and fills the molten metal M by abrupt pressure reduction in the cavity 9C and additional pressurization in the holding furnace 5, the molten metal flow in the cavity 9C. The property is very good. In particular, since the casting apparatus 1 is a casting space in which the cavity 9C of the mold 9 forms the cylinder head of the internal combustion engine, a high-quality cylinder head can be obtained with the above-described improvement in the hot water flow.

<Sixth Embodiment>
The casting apparatus 1 shown in FIG. 11A has the same basic configuration as that of the fifth embodiment, and the cavity 9C of the mold 9 is a casting space for molding the motor case.

  The mold 9 of this embodiment includes an upper mold 9U, a lower mold 9L, and a horizontal mold 9S, and a cavity 9C corresponding to the motor case is formed therebetween. The horizontal mold 9 </ b> S can be advanced and retracted with respect to the mold center by a drive device 20 including a cylinder 21 and a drive rod 22.

  As shown in FIG. 11B, a plurality of cores N4 for forming a water jacket are arranged in the cavity 9C. Further, the mold 9 in this embodiment is integrally provided with a space forming portion 9F for forming an internal space of the motor case. This space forming portion 9F hangs down from the center of the lower surface of the upper die 9U, and forms a cavity 9C that is a casting space for a thin motor case with the core N4.

  The casting apparatus 1 having the above-described configuration pressurizes the inside of the holding furnace 5 to raise the molten metal M to the vicinity of the pouring gate of the cavity 9C based on the above-described casting method, and then reduces the pressure in the cavity 9C and the inside of the holding furnace 5. The molten metal M is filled by additional pressurization.

Thereby, the casting apparatus 1 implement | achieves reduction of the installation cost and manufacturing cost by simplification of the decompression means 14 , and shortening of the cycle time of casting similarly to previous embodiment. Further, since the casting apparatus 1 stops the pressure reduction in the cavity 9C after a preset filling time has elapsed, the pressure reducing means 14 is stopped before the gas is generated from the core N4, and the pressure reducing means by the gas in the core 4 is used. 14 contaminations can be prevented in advance.

  Furthermore, since the casting apparatus 1 raises the molten metal M to the vicinity of the pouring gate 11 and fills the molten metal M by abrupt pressure reduction in the cavity 9C and additional pressurization in the holding furnace 5, the molten metal flow in the cavity 9C. The property is very good. In particular, since the casting apparatus 1 is a casting space in which the cavity 9C of the mold 9 molds the motor case, it is possible to obtain a high-quality motor case with the improvement of the above-described hot water flowability.

  Note that the casting method and casting apparatus of the present invention are not limited to the above embodiments, and can be applied to components having complicated structures such as suspension members, cylinder heads, and motor cases. Further, the pressurizing means is not limited to the one that pressurizes the molten metal with a gas, and includes one that pushes out the molten metal with electric power, such as an electromagnetic pump. Details of the configuration can be changed as appropriate without departing from the scope of the present invention.

1 Casting equipment (casting machine)
REFERENCE SIGNS LIST 5 Holding furnace 9 Mold 9C Cavity 11 Filler 16 Molten sensor 13 Pressurizing means 14 Depressurizing means 14A Intake pipe 14B Exhaust pipe 14C Vacuum tank 14D Vacuum pump 14E On-off valve 101 Casting apparatus 114 Decompression means 114A Branch pipe M Molten metal

Claims (7)

When molding a product based on the low-pressure casting method using a casting machine with a mold having a cavity on the upper side of the holding furnace containing the molten metal, the inside of the holding furnace is pressurized to the vicinity of the sprue of the cavity After being raised, the inside of the cavity is sucked and depressurized, and the holding furnace is further pressurized to fill the cavity with molten metal, and when the filling of the molten metal is completed, the depressurization in the cavity is stopped. Casting method. 2. The casting method according to claim 1, wherein pressurization in the holding furnace is stopped upon completion of solidification of the molten metal in the cavity . Using a melt sensor that detects the completion of filling the melt into the cavity,
3. The casting method according to claim 1, wherein the pressure reduction in the cavity is stopped when the melt sensor detects completion of the filling of the melt within a preset filling time. A casting apparatus to which the casting method according to claim 1 or 2 is applicable,
A plurality of casting machines including a holding furnace containing molten metal, a mold having a cavity, and a pressurizing means for pressurizing the inside of the holding furnace,
It includes a decompression means for sucking and decompressing the inside of the cavity of each casting machine,
The decompression means includes a vacuum tank having an intake pipe on the inlet side and an exhaust pipe on the outlet side, a vacuum pump connected to the exhaust pipe of the vacuum tank, and a cavity of each casting machine branched from the intake pipe of the vacuum tank A casting apparatus comprising: branch pipes communicating with each other; and an on-off valve that opens and closes the middle of each branch pipe.   5. The casting apparatus according to claim 4, wherein the mold cavity is a casting space for molding a suspension member for an automobile.   5. The casting apparatus according to claim 4, wherein the mold cavity is a casting space for molding a cylinder head of an internal combustion engine.   The casting apparatus according to claim 4, wherein the cavity of the mold is a casting space for molding the motor case.

Images